6644178665 has 4 divisors (see below), whose sum is σ = 7973014404. Its totient is φ = 5315342928.

The previous prime is 6644178649. The next prime is 6644178679. The reversal of 6644178665 is 5668714466.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 810427024 + 5833751641 = 28468^2 + 76379^2 .

It is a cyclic number.

It is not a de Polignac number, because 6644178665 - 2⁴ = 6644178649 is a prime.

It is a super-2 number, since 2×6644178665² = 88290220264882364450, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 664417862 + ... + 664417871.

It is an arithmetic number, because the mean of its divisors is an integer number (1993253601).

Almost surely, 2^6644178665 is an apocalyptic number.

It is an amenable number.

6644178665 is a deficient number, since it is larger than the sum of its proper divisors (1328835739).

6644178665 is a wasteful number, since it uses less digits than its factorization.

6644178665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1328835738.

The product of its digits is 5806080, while the sum is 53.

The square root of 6644178665 is about 81511.8314418220. The cubic root of 6644178665 is about 1879.9534718566.

The spelling of 6644178665 in words is "six billion, six hundred forty-four million, one hundred seventy-eight thousand, six hundred sixty-five".